<!DOCTYPE html>
<html lang="zh-CN">
    <head>
        <meta charset="UTF-8" />
        <title>03_盒子模型-特点-父元素高度塌陷</title>
        <style>
            #container {
                width: 500px;
                border: 1px solid black;
            }

            #container .item {
                float: left;
                width: 100px;
                height: 100px;
                background-color: aqua;
                border:1px solid black;
            }
        </style>
    </head>
    <body>
        <div id="container">
            <div class="item"></div>
            <div class="item"></div>
            <div class="item"></div>
        </div>
    </body>
</html>